Machine and method for making leak-proof paper bags



8. P. LOKEY Oct. 7, 1969 MACHINE AND METHOD FOR MAKING LEAK-PROOF PAPER mes Filed Aug. 23, 19s? 6 Sheets-Sheet l I NVENTOR Burke I? Lo/rey ATTORNEY B.P.LOKEY Oct. 7, 1969 MACRINE AND METHOD FOR MAKING LEAK-PROOF PAPER BAGS Filed Aug. 23, 1967 6 Sheets-Sheet 2 Oct. 7, 1969 LOKEY I I 3,470,796

MACHINE AND METHOD FOR MAKING LEAK-PROOF PAPER BAGS Filed Aug. 23, 1967 s Sheets-Sheet :5

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INVENTOR Bur/re Lakey ATTORNEY 5. P. LOKEY Oct. 7, 1969 MACHINE AND METHOD FOR MAKING LEAK-PROOF PAPER BAGS Filed Aug. 23. 1967 6 Sheets-Shea t 4 I NVENTOR w M A L P. W e m B M a. P. LOKEY 3,470,796

PROOF IAPER BAGS Oct. 7, 1969 I MACHINE AND METHOD FOR MAKING LEAK- Filed Aug. 23. 1967 6 Sheets-Sheet INVENTOR Burke P. Lo/rey QHU BY fl-y ATTORNEY Oct. 7, 1969 B. P. LOKE'Y 3,470,199

MACHINE AND METHOD FOR MAKING LEAK-PROOF PAPER BAGS v u 1. T 280 3 Burke R Lo/rey ATTORNEY United States Patent 3,470,796 MACHINE AND METHOD FOR MAKING LEAK-PROOF PAPER BAGS Burke P. Lokey, Metairie, La., assignor to Westvaco Corporation, a corporation of Delaware Filed Aug. 23, 1967, Ser. No. 662,773 Int. Cl. B31b 21/26, 31/02, 49/04 US. C]. 93-13 8 Claims ABSTRACT OF THE DISCLOSURE A machine for making seamless-bottom bags having leak-proof capability from an elongated bag blank of stifi paper, comprising adhesive applicator means for depositing longitudinal adhesive strips, which are uniform in thickness, from a selected springback distance on one side of the transverse center fold line of the bag blank to the end thereof on the other side of the fold line, tucking means, and nip roll means for folding the bag blank along the fold line, whereby the finished bag has a doubled quantity of adhesive along the springback distance.

Summary of the invention This invention relates to machines and methods for making bags of flexible material that can be adhesively joined. It particularly relates to making bags having leakproof capability that are formed with a seamless bottom and a leak-proof seam along each side. It specifically relates to large leak-proof bags that are formed of heavy paper having elastic resistance to folding. Bags of this design are described and claimed in US. patent application No. 539,036, now Patent No. 3,358,903.

Description of the prior art Machines in the prior art, as described in U.S. Patent No. 2,054,832, for example, generally use an adhesive-applying device of a constant-availability type that deposits a line of adhesive along each longitudinal edge of a continuously moving web, before or after longitudinal folding of continuous or partial edge strips. After cutting the web into lengths of material and transversely folding each length at the center thereof, the adhesive lines are mated to form adhesive seams having double quantities of adhesive material, if continuous edge strips are used, or single quantities of adhesive material, if edge strips are formed in alternate panels. in either situation, the quantity of adhesive is uniform and cannot be altered at will along the length of the adhesive seam.

To manufacture leak-resistant and leak-proof paper bags in large sizes, it is desirable to apply an extra quantity of adhesive in the bottom fold areas because of springback characteristics of paper and like materials. Springback is caused by elasticity of the folded material and creates a tendency for the conjoined surfaces to separate near the fold. springback can be a serious problem for bag made of heavy, stiff paper having an elastic resistance to folding.

When using the uniform adhesive supply systems of the prior art, if an adequate amount of adhesive is applied to a side seam for protection against leakage in the springback area, an excessive amount is applied to the remainder of the seam. If an adequate amount is applied in the springback area, much wastage of adhesive occurs along 3,470,795 Patented Oct. 7, 1969 the remainder of the seam, and excess adhesive may contaminate the interior of the bag.

It is the object of this invention to provide means and a method for applying a doubled quantity of adhesive on side seams of a bag in the springback area along a selected springback distance and a single quantity of adhesive on the remainder of the side seams.

Description of the drawings The machine for carrying out the method that fulfills this objective is shown in the accompanying drawings, as follows:

FIG. 1 is a side elevation, viewed from the operators side;

FIG. 2 is a plan view of the machine shown in FIG. 1;

FIG. 3 is a diagrammatic perspective view of the folder bar assembly and the compound linkage system for the adhesive applicator assembly;

FIG. 4 is a perspective view, from approximately the operators position and eye level, of the carriage assembly and the adhesive applicator assembly;

FIG. 5 is a cross-sectional elevation, looking from the operators side along the middle of the machine, just after a length of paper has reached its terminal position and the adhesive applicator assembly has contacted the surface of the paper;

FIG. 6 is a cross-sectional elevation similar to FIG. 5 except that the adhesive applicator assembly has travelled towards the right past the fold line, and the folder bar has tucked the paper length into the nip of the nip rolls;

FIG. 7 is a cross-sectional elevation similar to FIGS. 5 and 6 except that the paper length has been engaged by the roll nip and pulled nearby completely through it;

FIG. 8 is a top view of the conveyor belts for receiving and discharging the finished bags beneath the machine; and

FIG. 9 is an electrical control circuit.

This machine compriss a generally horizontal feed table 15 mounted on a rigid frame 10, a pair of transversely mounted rotating rolls 81, 82 having a downwardly urging nip 83, an automatically actuated compound linkage system, a folder bar assembly 40, a carriage assembly 50, an adhesive applicator assembly 60, a discharge conveyor 90, and a sensing-and-switching means which coordinates the automatic actuation of the compound linkage system with the automatic actuation of adhesive applicator assembly 60. Feed table 15 has a central transverse slot within which rolls 81, 82 are mounted so that their upper surfaces are substantially in the plane of the table top. Rolls 81, 82 are rotatably attached to frame 10 and are driven by an electric motor 115.

The machine receives lengths of heavy paper or like material, generally twice as long as the finished bag and herein designated as bag blanks 11 with gusset fins already formed along both sides as edge strips for a desired bag design. These bag blanks 11 travel endwise onto feed table 15. Back stop 16, attached along the back edge of feed table 15 and raised slightly thereabove, acts as an edge guide for bag blank 11. When the forward or lefthand end 12 of bag blank 11 strikes end stop at the left-hand end of feed table 15, bag-position switch 17 is tripped and the sen-sing-and-switching means actuates hydraulic cylinders that: (a) clamp bag blank 11 with the cylinder rod or bag clamp cylinder 19 so that bag blank 11 is held immobile; (b) bring adhesive applicator assembly 60 downwardly onto bag blank 11 at a selected springback distance to the left of nip 83; (c) start adhesive flow and more adhesive applicator assembly 60 to the right past nip 83; (d) tuck the center of bag blank 11 into nip 83, whereupon rolls 81, 82 pull the folded bag blank through nip 83 while adhesive applicator assembly 60 remains stationary and a steady quantity of adhesive flows onto the gusset fins; and (e) stop adhesive flow and raise adhesive applicator assembly 60 as the trailing end of bag blank 11 passes thereunder.

The compound linkage system comprises two hydraulic cylinders 30, 35 which are connected in series, as is clearly shown in FIG. 3. These cylinders 30, 35 are attached to frame along the back edge thereof. Adhesive-assembly cylinder 30 is attached by pin 29 to frame 10 and moves cylinder rod 31 which is attached by pin 34 to the upper end of adhesive pivot arm 33 which is attached to frame 10 by pin 32 at its lower end. Link arm 39 is also attached to pin 34 at one end and to rod 51 at the other end.

Carriage assembly 50 comprises rod 51, carriage 52, back plate 54, end plates 55, carriage block 57, and parallel rods 58, as is clearly shown in FIG. 4. Rod 51 is attached to carriage 52 and to link arm 39. Carriage 52 moves slideably from left to right, as seen in FIG. 4, on carriage blocks 57 that slide on parallel rods 58 which are attached at their ends to end plates 55. Back plate 54, to which end plates 55 are attached, is mounted on frame 10 and has a generally horizontal slot, with edges 53, through which rod 51 moves back and forth. Back plate 54 and end plates 55 form a channel-shaped extension of frame 10 for supporting parallel rods 58.

Adhesive applicator assembly 60 comprises applicator arm 61, gusset 62, applicator bar 63, pin 64, axle 65, support arm 71, adhesive cylinders 72, adhesive delivery lines 73, adhesive valve solenoids 74, and applicator heads 75, as shown in FIG. 5. The parts of adhesive applicator assembly 60 are movably supported by the parts of carriage assembly 50 and are moved back and forth by link arm 39 in response to movement of cylinder rod 31.

A generally upright applicator pivoting cylinder 102, having external switch 20 attached at one side, is attached to the right-hand side of carriage 52, as shown in FIGS. 1 and 2. Adhesive applicator assembly 60 is also attached by axle 65 to carriage -52, near the middle thereof. Applicator arm 61 pivots about axle 65 and has pin 64 at its right-hand end. Cylinder rod 101, which is moved by cylinder 102, is attached to pin 64. Applicator bar 63 is transversely attached to the left-hand end of adhesive arm 61. Gusset 62 strengthens this juncture.

A third attachment to carriage 52 is J-shaped strap 66, the short side of which protrudes upwardly through elon gated slot 104 in feed table 15. Back-up plate 67 is attached to the top of this short side and rides back and forth immediately above the top of feed table and generally parallel thereto, whereby it covers rotating rolls 81, 82 when adhesive applicator heads 75 are thereabove.

Adhesive applicator assembly 60, back-up plate 67, and applicator pivoting cylinder 102- move with carriage 52 and carriage blocks 57 on parallel rods 58 in response to movement of cylinder rod 31 as transmitted by link arm 39.

Returning to the compound linkage system as shown in FIG. 3, folder-arm cylinder 35, being attached to pin 34, is swingably attached to frame 10 and operates in series with adhesive-assembly cylinder 30. It moves cylinder rod 36 which is attached by pin 37 to the upper end of folder pivot lever 38. A transverse folder shaft 41, which spans the width of the machine and is supported in bearings by frame 10 beneath feed table 15, is rigidly attached to the lower end of folder pivot lever 38. Dual folder arms 42 are tightly attached to folder shaft 41 and are attached to transverse folder bar 43 having doubly-beveled tucking edge 44. As lever 38 is swung by cylinder rod 36, tucking edge 44 of folder-bar assembly 40 is raised from, or lowered into, nip 83.

Because cylinders 30, 35 are connected in series, tucking edge 44 of folder bar 43 enters nip 83 only when adhesive-assembly cylinder 30 is fully extended. The cycle begins as applicator pivoting cylinder 102 retracts its cylinder rod 101 and pivots adhesive assembly 60 downwardly while cylinder rod 31 of adhesive-assembly cylinder 30 is retracted to the extent that the selected springback distance requires. The cycle continues as cylinder rod 31 extends while adhesive is being deposited in smooth strips onto bag blank 11. Just before cylinder rod 31 is fully extended, cylinder 35 extends, thereby swinging folderbar assembly 40 in a clockwise direction, quickly bringing tucking edge 44 into contact with the transverse center line of bag blank 11 exactly as the cylinder rod of bagclamp cylinder 19 is retracted and adhesive applicator assembly 60 stops moving, so that bag blank 11 is released and motion of both sides of bag blank 11 toward nip 83 continues at the same linear rate as the previous motion of adhesive applicator assembly 60. As rolls 81, 82, which border nip 83, grasp the paper and pull both sides of bag blank 11 into and through the nip, the linear rate of movement of bag blank 11 is unchanged, and the strips of deposited adhesive are smooth and uniform, free of discontinuities, blobs, or irregularities because speeds of these three operations are substantially equal.

Discharge conveyor comprises drive rolls 91, 92, lower belt 93, upper belt 94, and idler rolls 95, 96. The nip of these rolls 91, 92 and belts 93, 94 is directly beneath nip 83. The machine of this invention can be operated with a hopper or with any conveyor of conventional design which removes finished bags from the work area. However, discharge conveyor 90 helps to hold conjoined sides of bag blank 11 in juxtaposed relationship while adhesive sets. The brief additional juxtaposition thus obtained can be of critical importance when forming bags from unusually stiff paper.

Bag-clamp cylinder 19 need not be used if an adhesive having very low viscosity is used and if adhesive applicator assembly 60 is adjusted so that applicator heads 75 produce negligible drag along the gusset fins of bag blank 11. Bag-clamp cylinder 19 is useful under production conditions, however.

(l) Bag blank 11 travels on feed table 15 until its lefthand end 12 contacts end stop while its far side is adjacent to back stop 16. In this position bag-position switch 17 is tripped (see FIG. 5").

(2) Either cycle button 13 or foot switch 111 is engaged and:

(a) relay 14 energizes and is latched by its contacts 14a, and (b) relay contacts 14b close, energizing:

(1) bag clamp valve solenoid 16 which causes bag clamp cylinder 19 to extend and clamp one end of bag blank 11 to feed table 15, and

(2) applicator arm position valve solenoid 18 which causes applicator cylinder 102 to retract (see FIG. 1). This brings applicator heads 75 into contact with bag blank 11.

(3) External switch 20 is closed by the retraction of the applicator arm cylinder 102, energizing relay 21. This relay latches when energized by its contacts 21a, then:

(a) relay contacts 21b close,

(h) current flows to the time delay relay 22 which is a network of rectifier, potentiometer, capacitor and relay, and

(c) folder arm valve solenoid 23 is energized, causing adhesive-assembly cylinder 30 to extend.

(4) Time delay relay 22 energizes after preset time and relay contacts 22a close, energizing valve solenoids 74. The belt melt valve cylinders 72 extend, thereby turning on the flow of holt melt adhesive. This causes lines of adhesive to be placed on the gusset fins as carriage 52 (see FIGS. 3 and 4) moves to its right-hand position.

(5 As adhesive-assembly cylinder 30 continues to extend andreaches a position /1, inch from its right-hand position, external switch 24 is closed, energizing relay 25 which latches through relay contacts 25a. Relay contacts 25b open, causing valve 16 to de-energize and the bag clamp cylinder 19 to retract, releasing the bag blank 11.

(6) As the adhesive-assembly cylinder 30 continues to extend, folder bar 43 strikes the center of bag blank 11 and pushes it into nip 83 of nip rolls 81, 82 (see FIG. 6). Nips rolls 81, 82 then assume control of bag blank-11 and pull the center of the bag through nip 83 and push the folded blank into the nip of conveyor rolls 91, 92 and belts 93, 94 (see FIGS. 7 and 8). This action brings the two sides of the bag blank into contact with each other, and causes the adhesive to conjoin the {opposing gusset fins.

(7) As adhesive-assembly cylinder 30 extends to its full extended position, external switch 26 is closed, energiz- (a) relay 27 which latches through contact 27a,

(b) folder arm valve solenoid 28a which causes folder-arm cylinder 35 to retract. As this cylinder retracts, folder bar 43 moves away from nip rolls 81, 82 about 1 inch, and

(c) relay contacts 27b open.

(8) As the bag moves through discharge conveyor 90,

its leading edge strikes external limit switch 107, energizing relay 86. This causes relay contacts 86a to open, de-energizing relay 14, opening relay contacts 14a and 14b, and:

(a) applicator position solenoid valve 18 de-eneri gizes, and cylinder 102 extends, raising applicator heads 75 away from bag blank 11;

(b) relay 21 de-energizes, opening relay contacts (c) relay 22 de-energizes, opening relay contacts 22a and de-energizing solenoid valves 74 which causes holt melt cylinder 72 to cut off adhesive flow;

(d) folder arm valve 23 de-energizes, causing folderarm cylinder 30 to retract;

(e) relay 27 de-energizes, opening relay which contacts 27a. Solenoid valve 88 for folder arm deenergizes, causing folder-arm cylinder 35 to extend. Also relay contacts 27b close;

(f) relay 25 de-energizes and relay contacts 86a close. (Another cycle can be started as soon as solenoid valve 86 de-energizes after the leading edge of the bag trips switch 17 because relay con tacts 27b provide a latching circuit for relay 14. If relay contacts 27b were not provided, relay 86 would energize, opening relay contacts 86a and de-energizing relay 14 circuit as soon as relay 21 was energized, again letting current flow through relay contacts 21b into relay 86.) l

(9) The bag continues to travel through the conveyor belts until it is discharged from the machine.

() The unit is now ready to start a new cycle (as soon as step 8 is complete).

It can readily be seen from the foregoing description that the instant method of depositing a doubled amount of adhesive in the springback area depends upon moving applicator assembly 60 to the left of nip 83 (as seen in FIG. 1) and bringing applicator heads 75 down onto bag blank 11 at a selected springback distance to the left of nip 83. While adhesive is being forced out after adhesive valve solenoids 74 open, applicator heads 75 move smoothly to the right past nip rolls 81, 82, remaining always over back-up plate 67. Exactly as applicator heads 75 stop moving, the right-hand portion of bag blank 11 moves leftwards therebeneath as nip rolls 81, 82 engage bag blank 11. The result is that smooth, continuous strips of adhesive are deposited without thinned sections, blobs, or discontinuities from the initial deposition point to the right-hand trailing edge of bag blank 11. When panels are mated in nip 83, there is a doubled thickness of adhesive in the springback areas and a single thickness in the remainder of the seams.

I claim:

1. A machine for making seamless-bottom bags from a bag blank of stiff paper having springback characteristics after folding, comprising:

(A) a rigid frame,

(B) a generally horizontal feed table which is mounted on said fram for supporting said bag blank, said table having a central transverse slot therein,

(C) a pair of rolls which are rotatably attached to said frame and are mounted within said slot so that the upper surfaces of the rolls are substantially in the plane of the table top, said rotatable rolls having a downwardly urging nip which is approximately beneath the transverse center line of said bag blank,

(D) an automatically actuated compound linkage system which is attached to said frame,

(B) an automatically actuated folder bar assembly which is attached to said frame, having a folder bar which canbe selectively lowered into said nip in response to hydraulic movement of said compound linkage system,

(F) an automatically actuated adhesive applicator assembly, which is movably attached to said frame, for depositing at least two parallel strips of adhesive on said bag blank in response to hydraulic movement of said compound linkage system, beginning at a selected springback distance on one side of said transverse center line and terminating at the end of said bag blank on the other side of the transverse center line, and

(G) sensing-and-switching means for automatic actuation of said compound linkage system, said folder bar assembly, and said adhesive applicator assembly.

2. The machine of claim 1 wherein said compound linkage system comprises:

(A) an adhesive-assembly cylinder, attached to said frame, which moves said adhesive applicator assembly along said selected springback distance toward and beyond said nip,

(B) a folding cylinder, swingably attached to said frame and operating in series with said adhesive-assembly cylinder, which moves said folder bar assembly toward said feed table, whereby said folder bar strikes the bag blank at said transverse center line and tucks the stiff paper into said downwardly urging nip, and

(C) means for returning said adhesive-assembly cylinder and said folding cylinder to respective starting positions.

3. The machine of claim 2 wherein said adhesive applicator assembly is movably supported on a carriage assembly comprising a channel-shaped extension of said frame, parallel rods attached thereto, and a carriage plate which is slideably supported by said parallel rods.

4. The machine of claim 3 wherein the adhesive applicator assembly comprises:

(A) an elongated applicator arm which is pivotably attached to said carriage,

(B) an applicator bar which it attached to one end of said applicator arm,

(C) at least two applicator heads which are attached to said applicator bar, and

(D) adhesive valve means which are attached to said applicator heads and are responsive to said sensingand-switching means.

5. The machine of claim 4 wherein an applicator pivoting cylinder it attached to said carriage and to the other end of said applicator arm, whereby said adhesive applicator assembly is selectively pivoted onto said bag blank.

7 8 6. The machine of claim 5 wherein a back-up plate is References Cited attached to said carriage and moves back-and-forth while UNITED STATES PATENTS 1n parallel relation to the top of said table and in supporting relation to said bag blank and to said applicator heads. 241,830 5/ 1331 Stocking 93-13 7. The machine of claim 1 wherein a clamp means is 5 2,014,497 9/1935 Haskell 9313 attached to said frame and is actuated by said sensing- 2,903,946 9/1959 Honsel 93-13 and-switching means, whereby said bag blank is immobilized until movement of said folder bar assembly begins. BERNARD STICKNEY, Primary Examine 8. The machine of claim 1 wherein a discharge conveyor, which is attached to said frame beneath said table, 10 U.S. Cl. X.R.

receives folded bag blanks from said nip and discharges the bag blanks from the machine. 93-8, 35; 118-9 

